Starter mechanism for thread rolling machine



April 1967 E. G. GROHOSKI ETAL 3,314,261

STARTER MECHANISM FOR THREAD ROLLING MACHINE Filed Nov. 18, 1964 INVENTORS EDWARD (S. GROHOSKI ROBERT D. MORTON BY fwd/'3 ATTORNEYS 70 United States Patent 3,314,261 STARTER MECHANESM FOR THREAD ROLLING MACHINE Edward G. Grohoski, Litchfield, and Robert D. Morton,

West Hartford, Conn, assignors to Hartford Special Machinery Company, Simsbury, Conn., a corporation of Connecticut Filed Nov. 18, 1964, Ser. No. 412,022 8 Ciaims. (Cl. 72-90) This invention relates to improvements in starter mechanisms for thread rolling machines of the reciprocating type.

In thread rolling machines of the reciprocating type such as disclosed in US. Patent No. 3,117,473, one of the most important and critical components is the starter mechanism. This mechanism is the part of the mechine whose function is to insert a headed blank between a stationary and a moving die at the instant the moving die comes to a position at the completion of its backstroke and reverses direction. At that time and in that position the dies are matched; i.e., the thread crests are opposite thread roots and the blank as it is then started and asit rolls on across the dies will have a thread which will track both dies without shaving the flanks of the thread. Therefore, a primary requirement of the starter mechanism is that it places a blank in the rolling position in the throat between the two dies at least by the time the moving die reverses its direction.

Adjustments in the starter actuation are made during setup while the machine is being turned over by hand; i.e., at very low speed, and it is quite important that the starter mechanism must also operate at its normal high operating speed the same way as it does during the very slow speed adjustment. Therefore, the starter mechanism should be constructed such that effects of inertia are minimal. Otherwise, it is practically impossible to put the machine in match; i.e., adjust it correctly at the high operating speed, except by trial and error taking much time and labor. The motion of the starter mechanism is initiated and timed by the motion of the moving die by means of a cam which is driven by the main crank of the machine. Due to accasional misfeeds which must be considered and accommodated, a solid connection between the cam and starter mechanism may not be used, thus necessitating some sort of overload release.

An additional complication arises from the fact that a large percentage of fasteners, the threads of which are rolled on fiat die machines, have tapered points rolled from a straight shank blade. Therefore, the threading dies are made with pointed sections which project beyond the die face. With this arrangement, if the starter mechanism opens a gate at the end of a column of blanks in a feed rail before the end of the pointing section of the moving die has moved past, there will be a great danger that the flat end of the pointing section will strike the bottom end of the blank and drive it back against the starter with the full power of the retracting slide. To prevent this the starter mechanism must operate open the feed rail gate only after the end of the moving die has moved past on the backstroke.

All of the foregoing point up the complications which arise in providing a starter mechanism which must operate at a very high speed and therefore must perform its intended function in an extremely short time, and must also be very accurate even at these high speeds. For example, at a machine production rate of 400 pieces per minute the starter must open a feed gate, remain open long enough for the end blank to move against the face of the moving die, and then push the blank across into the throat between the moving die and the roll on portion of a stationary die in about 35 milliseconds (.035

3,314,251 Patented Apr. 18, 1967 "ice second). Also, the starter mechanism must operate at full machine speed in exactly the same manner as it does during setup when the machine is turned over by hand, otherwise the threads will not be rolled correctly and the thread flanks will be shaved.

In view of the foregoing, the objects of this invention are:

To reduce weight and inertia of the moving components of a starter mechanism to a minimum without sacrificing strength.

To eliminate heavy turning moments and support a starter blade by means of oscillating pivots from a bracket substantially the same level as the blade.

To provide for a substantially straight line motion of a starter blade while in operation.

To provide adjustment for the length of the starter blade stroke thereby allowing accommodation of screw blanks of different diameters without requiring change in the throw of the actuating cam.

Other objects will be in part obvious and in part pointed out more in detail hereinafter.

The invention accordingly consists in the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereafter set forth and the scope of the application which will be indicated in the appended claims.

In the drawings:

FIG. 1 is a partial top plan view of a portion of a thread rolling machine showing the starter mechanism which is the subject of this invention.

FIG. 2 is a front elevational view of the starter mechanism shown in FIG. 1.

vReferring to the drawings, a thread rolling machine, for example, of the type shown in US. Patent No. 3,117,473, includes a machine table 10 supporting a fixed die 12 having a thread rolling face 16. A movable die 14 is mounted for sliding movement with its thread rolling face 18 parallel to and spaced from the thread rolling face 16 of fixed die 12. A plurality of blanks 22 are fed by gravity down inclined feed track 20, which consists of a pair of feed rails 21, 21, into position to be inserted between the moving and stationary dies by means of the starter mechanism and feed control 26 which is the subject of this invention. A movable die drive means 24 is provided for moving the movable die 14.

The arrangement of the feed track 20, stationary and movable dies 12 and 14, and drive means 24 for the movable die as well as other usual adjusting means, etc., are known in the prior art and may be like that shown in US. Patent 3,117,473.

The starter mechanism and feed control 26 which is the subject of this invention includes a starter blade 28 having a working end 29 for inserting a blank 22 between the working faces 16 and 18 of these stationary and movable dies 12 and 14 respectively. The blade 28 is attached to a starter blade bracket 3t? by means of an attaching screw 32. There is an enlarged hole 34 in the blade 28 to allow for adjustment in the mounting of the blade on the bracket.

The starter blade bracket 30 has an elongated body 36 which includes pivots 38 and 40. The starter blade bracket 30 is swingably mounted about oscillating pivot means from a block 42 Which is attached to the machine table 10 by screws 44 and includes an upstanding boss 46 having pivots 48 and 59. A pair of links 52 and 54, FIGS. 1 and 2, connect between pivots 48 and 38 and a similar pair of shorter links 56 and 58 connect between pivots 40 and 50. Pivot pins 60, c2, 64 and 66 are provided to connect the links to the block 42 and starter bracket 30 at pivots 38, 40, 48 and 50, respectively.

The use of a slide support for a thread roller starter is objectionable and oscillating pivots for the starter are much simpler and far more preferable. In prior Patent No. 3,117,473 the starter was mounted for swinging about a single pivot necessitating a heavy elongated arm. By having the arrangement of this invention however, the starter blade 28 is swingable by means of the linkage including links 52, 54, 56 and 58 from a pair of stationary pivots 48 and 50 and the links 56 and 58 are shorter than the links 52 and 54 providing an arrangement for nearly straight line movement of the working end 29 of the starter blade 28. This simple and lightweight assembly is quite strong and also eliminates heavy turning moments which might occur with a large offset single pivot. Further, the straight line motion keeps the blade 28 from swinging into the path of the movable die 14. This construction also reduces the weight and hence, the inertia of the rapidly oscillating starter blade 28 and its actuating mechanism.

For operating the starter blade 28 there is provided a cam 68 with a feed control contour 69. A cam follower assembly 70 includes a cam roll 71 mounted on cam roll arm 72. The cam roll arm is linked by pivot 73 to a pair of connected fulcrum arms 74, 74 which are normally stationary but may oscillate about a stationary post 75' afiixed to the machine table to assume one of two positions fixing different positions of the pivot 73 as shown in solid and phantom lines in FIG. 1. The cam roll arm 73 includes a slot 76 in which a yoke 78 is adjustably positioned by means of a bolt 77. The yoke 78 is attached to collar 92, which in turn is adjustably threaded into turnbuckle link 79. Link 79 in turn is threaded to a collar 89 extending around pin 62 so that longitudinal movement of the turnbuckle link causes movement of the swinging linkage and movement of the starter blade 28. It can be seen that the length of stroke of the starter blade can be adjusted by adjusting the position .of the turnbuckle yoke 78 in the slot 76- without requin'ng any change in the throw of the cam 68, thereby allowing the cam roll to remain in contact with the cam at all times and providing for smooth starting action without slamming. The length of stroke of the starter blade 28 would be varied as desired to suit the spacing of track rails 21, 21 required for feeding blanks of varying diameters by this adjustment. Additional adjustment for the starter blade position with regard to the feed track may be obtained by adjusting the turnbuckle link 79.

For biasing the cam roll 71 against cam 68 and providing an overload release there is provided a spring 81 7 within a spring housing 89 forcing plunger 82 downward as viewed in FIG. 1 against a finger link 83 which link is connected about pivot pins 62 and 66. Thus movement of the end of finger link 83 by the force of spring 81 moves the linkage to the right as viewed in FIG. 1 and moves the cam roll 71 to the left as viewed in FIG. 1 toward the cam 68. Because spring 81 functions as the starter drive power as well as to hold the cam roll 71 in contact with the cam 68, in the event of an obstruction, such as a jammed blank in the way of the starter blade, the compression spring provides an overload release. That is, the force of spring 81 which furnishes the feeding force will not overcome the force of a jammed blank and therefore the machine will not be damaged due to one jammed blank.

A control assembly 84 is also provided to control the position of fulcrum lever 74 and this assembly includes an adjustable stop 85 for contacting the fulcrum lever in the full line position of FIG. 1. In this position the spring 81 furnishes the driving force and the cam 69 paces the operation of the starter blade 28. However, to cease the feeding action the control assembly 84 may be operated to move the stop 85 upwards and then spring 86 in spring housing 87 which biases plunger 88 onto the end of fulcrum lever 74 causes the lever to follow the stop 85 to the phantom line position shown in FIG. 1. In this position the cam roll 71 is removed from the cam by virtue of movement of the pivot point 73 for cam roll 4 arm 72. With the cam roll 71 out of contact with the cam the feeding action ceases but the starter blade is biased by the spring 81 to close off the feed track 20 and feed is shut off. The spring 86 holds the fulcrum lever in a stationary position against the stop 85 of control assembly 84.

During setup the starter blade 28 may be intentionally retracted from below feed track 28 by rotating shoe 90 attached to rotatable rod 91 so that the shoe 90' contacts the finger link 83 and moves the parallel linkage to the left as viewed in FIGURE 1.

A typical operating cycle of a machine embodying this invention involves loading the headed blanks 22 in the feed track 20 while operation of the starter mechanism 28 will feed the blanks 22 one at a time and in timed relation between the stationary die 12 and the reciprocating movable die 14.

The operation of the starter mechanism and feed control is paced by cam 68 and cam contour 69 under the force of spring 81 biasing link 83 and hence the linkage carrying the starter 28 to the right as viewed in FIGURE 1 to close off the feed. At the time cam contour 69 is aligned with cam roll 71, however, the spring 81 which also causes the cam roll 71 to follow the contour of the cam causes the starter blade -28 to retract to allow blank 22 to be fed on top of the movable die 14 at the exact moment required. The further rotation of cam 58 causes spring 81 to move the starter blade 28 forward to force the blank 2-2 between the two dies at the precise time the dies have their threads matched. Adjustment of the length of stroke of the starter blade 28 is obtained by means of the slot 76 which allows for an adjustable position of the turnbuckle link 79 on the came roll arm 72.

In normal operation the control assembly 84 is in the full line position shown in FIG. 2 but may be moved to the phantom line position to pivot fulcrum arm 74 and move the cam roll 71 out of contact with the cam 68 thus ceasing the feed and leaving starter blade 28 in the full line position under the bias of cam 81.

During the setup and for adjusting purposes the rod 91 is rotated to withdraw the blade 28 from below the feed chute 20.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to the preferred embodiment, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and units operation may be made by those skilled in the art without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the following claims.

We claim:

1. A starter mechanism for a thread rolling machine of the reciprocating type including, a first fixedly mounted thread rolling die, a second thread rolling die movably mounted and reciprocatingly driven parallel to the first die, means for feeding work blanks to a position adjacent a starting end of the first die, and a starter mechanism for gating the work feeding means and wedging a work blank between the starting ends of the first and second dies, the starter mechanism comprising; a starter blade, a swinging linkage including at least two pivotable links supporting the starter blade for substantially straight line movement, and means for driving the linkage.

2. A starter mechanism for a thread rolling machine as defined in claim 1 wherein the swinging linkage includes at least two links of unequal length connected in generally parallel relationship to the starter blade and a fixed support.

3. A starter mechanism for a thread rolling machine as defined in claim 1 wherein the starter blade reciprocation is controlled by a cam and a cam follower linkage assembly which includes an adjustable means to allow variation in the amount of Starter blade movement.

4. A starter mechanism as defined in claim 1 wherein the starter blade is biased toward feeding position by a spring means acting upon the swinging linkage and is paced for retraction by a cam contacted by a cam follower assembly connected to the swinging linkage.

5. A starter mechanism as defined in claim 4 wherein the cam follower assembly includes a turnbuckle link adjustably mounted on a slot in a cam follower arm.

6. A starter mechanism as defined in claim 5 wherein the cam follower arm is pivotably supported from a fulcrum arm which in turn is pivoted from a fixed support and a control assembly cooperates with the fulcrum arm to determine an operative or non-operative position of the cam follower arm.

7. A starter mechanism as defined in claim 6 wherein there is a spring means biasing the fulcrum arm and a stop positioned by the control assembly.

8. A starter mechanism for a thread polling machine of the reciprocating die type including, a table, a first thread rolling die fixedly mounted on the table, a second rolling die, means mounting the second die in spaced relation to the first die and for movement substantially parallel thereto, means for feeding work blanks to a position adjacent the starting end of the first die, and a starter mechanism for gating the feeding means and for wedging a workpiece between the starting ends of the first die and second die, the starter mechanism comprising; a starter blade, a swingable parallel linkage for supporting the starter blade from the table, the parallel linkage including at least two parallel links of different lengths pivotably supporting the starter blade for substantially straight line movement thereof, spring means for biasing the starter blade in a blank feeding direction, cam means for pacing the movement of the starting blade, and cam follower means connecting the cam means to the swingable parallel linkage, the cam follower means including means for adjusting the length stroke of the starter blade.

References Cited by the Examiner UNITED STATES PATENTS 1,696,225 12/1928 Blood 72-90 FRANCIS S. HUSAR, Primary Examiner. 

1. A STARTER MECHANISM FOR A THREAD ROLLING MACHINE OF THE RECIPROCATING TYPE INCLUDING, A FIRST FIXEDLY MOUNTED THREAD ROLLING DIE, A SECOND THREAD ROLLING DIE MOVABLY MOUNTED AND RECIPROCATINGLY DRIVEN PARALLEL TO THE FIRST DIE, MEANS FOR FEEDING WORK BLANKS TO A POSITION ADJACENT A STARTING END OF THE FIRST DIE, AND A STARTER MECHANISM FOR GATING THE WORK FEEDING MEANS AND WEDGING A WORK BLANK BETWEEN THE STARTING ENDS OF THE FIRST AND SECOND DIES, THE STARTER MECHANISM COMPRISING; A STARTER BLADE, A SWINGING LINKAGE INCLUDING AT LEAST TWO PIVOTABLE LINKS SUPPORTING THE STARTER BLADE FOR SUBSTANTIALLY STRAIGHT LINE MOVEMENT, AND MEANS FOR DRIVING THE LINKAGE. 